The lower the voltage, the longer the coil needs to charge (dwell) - and if the voltage is too low, then there isn't enough time to sufficiently charge the coil before it has to fire.
I've seen plenty of reports of rough running cars suddenly fixed by replacing a failing battery.
I don't believe it's specifically the ECU causing the problem in these cases, it's one of the more tolerant parts of the EMS considering it sources all it's power via an internal 5v regulator.
One theory I have on the failing battery scenario is if the battery has no charge depth, then the voltage drops sharply with load.
So when the ECU calculates dwell and injector pulse, it uses the 'unloaded' battery voltage which might be say 13v.
But as soon as it fires the injectors, the ~4A draw drags the battery's voltage down much lower than the ECU anticipates - so the injector opening time is nowhere near long enough to counteract the sudden voltage drop and the result is not enough fuel gets injected.
Similar with the coils - the dwell is calculated on the unloaded battery voltage. But as soon as the coil is energised, the ~10A load drags the voltage right down and the dwell time is not enough to produce a decent spark.
But as soon as the injectors close and the coil isn't charging, the battery voltage bounces back up, ready to fool the ECU for the next cycle
The alternator doesn't react fast enough to counteract these sudden loads - typical coil charging time is ~0.006 seconds and injectors at low load are open for an order of magnitude less.
Whereas a healthy battery will keep the voltage much more stable during these transient loads, so the ECU's calculations will be correct.
Well that's my theory anyway - not that it actually relates to your original question though, but might help explain why stable voltages and healthy batteries are important for EFI